264 NICHOLS: THE VEGETATION OF CONNECTICUT 
there may be one or more. These have attained their present 
condition through the downcutting of the rivers into the deep 
fill of glacial drift and outwash.* The effect of the changed 
topographic relations on these former flood plains as habitats for 
plants is readily comprehended. With the lowering of the river 
they must gradually have become more and more xerophytic and 
thus less and less tenable for the flood plain mesophytes. The 
actual effect of these changes on vegetation can only be con- 
jectured. For, just as has been pointed out in the case of rock 
ravines, the period of time involved has been so great that oscilla- 
tions in climate as well as changes in topography must presumably 
be taken into account. At the present day the vegetation of river 
and stream terraces is perhaps best treated with that of uplands, 
since the river has long since ceased to act as a dynamic factor in 
its development. 
ACKNOWLEDGMENTS 
For suggestions in connection with the preparation of this 
paper, the writer is greatly indebted to Professor Joseph Barrell, 
of the Geological Faculty, and Professor A. W. Evans, of the 
Botanical Faculty of Yale University, and to Mr. C. A. Weatherby, 
of East Hartford. 
SHEFFIELD SCIENTIFIC SCHOOL OF YALE UNIVERSITY 
* In this connection, see Rice, W. N., & Gregory, H. E., Manual of the Geology 
of Connecticut. Conn. State Geol. and Nat. Hist. Surv. Bull. 6: 35, 36- 1900. 
